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Postmortem human eyes were subjected to optic nerve (ON) traction in adduction and elevated intraocular pressure (IOP) to investigate scleral surface deformations. We incrementally adducted 11 eyes (age 74.1 ± 9.3 years, standard deviation) from 26° to 32° under normal IOP, during imaging of the posterior globe, for analysis by three-dimensional digital image correlation (3D-DIC). In the same eyes, we performed uniaxial tensile testing in multiple regions of the sclera, ON, and ON sheath. Based on individual measurements, we analyzed eye-specific finite element models (FEMs) simulating adduction and IOP loading. Analysis of 3D-DIC showed that the nasal sclera up to 1 mm from the sheath border was significantly compressed during adduction. IOP elevation from 15 to 30 mmHg induced strains less than did adduction. Tensile testing demonstrated ON sheath stiffening above 3.4% strain, which was incorporated in FEMs of adduction tethering that was quantitatively consistent with changes in scleral deformation from 3D-DIC. Simulated IOP elevation to 30 mmHg did not induce scleral surface strains outside the ON sheath. ON tethering in incremental adduction from 26° to 32° compressed the nasal and stretched the temporal sclera adjacent to the ON sheath, more so than IOP elevation. The effect of ON tethering is influenced by strain stiffening of the ON sheath.

This paper presents an analytical and finite element modeling (FEM) investigation on the carbon fiber reinforced polymer concrete-filled polyvinyl chloride tube (CCFPT) concrete columns under axial eccentric compression. The study involved collecting experimental data from 32 CFPT columns confined with CFRP from literature and modeling them using FEM in ABAQUS. A parametric study was conducted on 260 CCFRP concrete columns, examining various parameters such as eccentricity, number of CFRP layers, thickness of PVC tube, column slenderness ratio, CFRP spacing, thickness of CFRP strips, confined concrete strength, and concrete core diameter. The effects of these parameters on the ultimate load and strain capacity were analyzed. Analytical models were developed to express the confined concrete strength and strain as functions of the constituent properties and dimensionless confinement parameters. The findings revealed that increasing eccentricity significantly reduced the ultimate load (up to 45%) and strain (up to 67%) capacities. Adding more layers of CFRP increased strength and strain capacities by 25% when going from 2 to 3 layers at a 20 mm eccentricity. Thicker PVC tubes increased load capacity by preventing buckling, but had inconsistent effects on strain. Higher slenderness ratios decreased both capacities, particularly strain. Six machine learning models were employed to predict the load-carrying capacity and confined ultimate strain. Various performance metrics, data visualization techniques, SHAP analysis, sensitivity analysis, and error characteristic curves were used to evaluate the prediction performance and analyze the impact of input parameters. The findings revealed that increasing eccentricity and CFRP layers lead to reduced ultimate load and strain capacities, while higher slenderness ratios result in increased ultimate loads. The study concluded that CCFPT columns with optimized CFRP wrapping can offer superior performance for eccentrically loaded columns. [ABSTRACT FROM AUTHOR]

Today, there is a high demand and increasing trend for multifunctional composite materials and components due to the combination of a wide range of favorable properties. However, undesired deformation leading to delamination, curvature, cracks, or even complete fracture frequently occurs during the co‐sintering process of metal–ceramic laminates (MCLs). To solve these issues, experimental work highly relies on the time‐consuming trial‐and‐error principle. This work aims to develop a thermo‐mechanical‐metallurgical model capable of predicting the densification, deformation, and delamination of MCLs during the co‐sintering process. It is found that the developed model successfully considers the inhomogeneous relative density distribution and phase transformation of the steel tape. In addition, a thin interlayer formed by a mixed slurry in the MCLs is modeled as cohesive elements to simulate the delamination process. The developed model is systematically validated by the experimental measurements and observations in terms of densification, deformation, and delamination during the co‐sintering process of the investigated laminate variants. [ABSTRACT FROM AUTHOR]

Loading–unloading is a ubiquitous phenomenon in engineering applications and an enduring topic in contact mechanics. Yield plateau and strain hardening are essential for material behaviors, but they have not been well considered in contact mechanics. This work developed a three-phase constitutive model to accurately describe the elastoplastic contact behaviors considering both yield plateau and strain hardening, merging the elastic-perfectly plastic and power-law hardening behaviors. The significance of the yield plateau and strain hardening was emphasized, and new empirical formulations of dimensionless contact load, area, and residual interference were presented, expanding the present knowledge of the elastoplastic contact problem. [ABSTRACT FROM AUTHOR]

The deterioration of the US transportation highway network and the onset of new technologies in the freight industry are expected to cause changes in the axle load magnitude and distribution, further exacerbating the reduction in the service life of flexible pavements. In this study, a reviewed framework to incorporate roughness-induced dynamic wheel loading into tire–pavement contact stress prediction is presented. The response to nonfree-rolling conditions, usually overlooked, was considered. State-of-the-art numerical models were used to account for pavement unevenness, vehicle dynamics, and 3D and nonuniform contact stresses. In this framework, for a given target international roughness index, an artificial multitrack roughness profile was converted into a dynamic loading profile based on the mechanical properties of a Class 9 vehicle. Upon discretization of the dynamic loading profile into a finite number of loads based on percentile distributions, a 3D finite element model of a dual-tire assembly was used to predict the contact stress distribution over a rigid surface. The performed numerical simulations allowed us to analytically quantify the variation of vertical and in-plane contact stress distribution. Hence, changes in the stress/strain field distribution and peak values under various axle loading scenarios were determined. The findings reveal that disregarding the effect of road roughness and vehicle maneuvering could result in considerable underestimation of the net forces and contact stress distribution developed at the tire–pavement interface. These considerations are particularly impactful on in-plane contact stresses, which, in turn, are associated with near-surface distresses. Practical Applications: The distribution of contact stresses at the tire–pavement interface influences the likelihood of failure near the surface and is greatly affected by driving behavior (braking, cornering, and acceleration). Truck electrification is likely to modify driving behavior due to the instant torque availability provided by electric powertrains, and the incorporation of battery packs is likely to alter the distribution of axle loading. The impact of these variables on the applied load to a pavement system could be further exacerbated by road conditions. In that regard, this paper aims to quantify the changes in the contact stress distribution when roughness, driving behavior, and axle loading are compounded. Because these considerations are not taken into account by current pavement analysis procedures, pavement engineers can use the results to assess the importance of each parameter on load characterization, a controlling variable on the prediction of pavement responses. [ABSTRACT FROM AUTHOR]

This paper investigated the hysteresis performance of multi-story Y-shaped eccentrically bare braced steel frames with block slit dampers (BSDs). After validating existing models through finite element (FE) analysis, an FE model of Y-shaped eccentrically bare braced steel frames (YEBFs) with BSD (BSD-YEBFs) was established. The influences of different types of BSDs on the hysteresis performance of YEBFs were subsequently analysed, as were the seismic performances of YEBFs with BSD (BSDF) and traditional Y-shaped eccentrically bare braced steel frames (TEBF) under cyclic loading, including the stress failure mode, hysteresis curve, stiffness, strength, and energy dissipation capacity. The results showed that: (1) compared with those of BASE-Y, the ductility coefficients of YEBFs with one level BSD (BSD-1) and two level BSD (BSD-2) increased by 59.57% and 39.47%, respectively, and the lateral bearing capacity decreased by 3.26% and 2.78%, respectively. (2) Compared with those of TEBF, the yield bearing capacity and ultimate bearing capacity of BSDF increased by 3.13% and 11.12%, respectively, and the ductility coefficient increased by 56.7%. Moreover, BSDF possesses higher initial stiffness and more sustained energy dissipation capabilities. [ABSTRACT FROM AUTHOR]

The increasing use of large glass surfaces in modern architecture requires robust adhesive solutions that balance aesthetic appeal with structural resilience, particularly in timber–glass applications. This study examines the influence of primer treatments on the shear performance of timber–glass adhesive joints, employing a combination of experimental testing and simulation techniques. Double-lap shear tests with epoxy adhesives assess the impact of various surface treatments on joint stiffness, shear stress distribution, and deformation. Additionally, a finite element model is developed to simulate joint behavior, evaluate failure modes, and analyze displacement patterns. Results indicate that primer applications notably enhance structural integrity by reducing displacement and increasing joint stability, thereby supporting more durable timber–glass assemblies. These findings offer valuable insights for advancing adhesive technologies in architectural components, enabling a closer alignment between structural performance and design innovation in timber–glass systems. [ABSTRACT FROM AUTHOR]

The increasing use of aluminum alloys in various industries necessitates the development of improved welding techniques. This study investigates the application of ultrasonic vibration in tungsten inert gas (TIG) welding of aluminum 5083 sheets. The results indicate that ultrasonic vibration significantly improves weld penetration depth and width, refines the microstructure by increasing the proportion of equiaxed grains, and enhances the mechanical properties of the welds, including tensile strength, and hardness. These findings demonstrate the potential of ultrasonic-assisted TIG (U-TIG) welding to optimize weld quality and performance in aluminum 5083 alloys. Finite element modeling of TIG and U-TIG welding provided heat distribution and temperature history, essential for analyzing microstructural observations and mechanical test results. Notably, previous U-TIG finite element modeling was inadequate, but this research offers a more accurate approach. The temperature results from the finite element model showed excellent agreement with reference data. The welding area was divided into three zones: fusion zone (FZ), partially melted zone (PMAZ), and heat affected zone (HAZ). Experimentally, TIG welded samples had FZ width and depth, and PMAZ width of 2.2, 1.45, and 0.4 mm, respectively, while U-TIG welding samples measured 1.95, 1.85, and 0.4 mm, respectively. Finite element modeling determined these zones to be 2.1, 1.5, and 0.45 mm for TIG welding, and 1.9, 1.9, and 0.4 mm for U-TIG welding, respectively. The mechanism of grain refinement was identified as dendrite fragmentation and heterogeneous nucleation. [ABSTRACT FROM AUTHOR]

Steel I-beams may be subject to deviation from their normal path towards the lateral direction due to obstacles along their axis line. This deviation in the lateral direction, i.e., the out-of-plane distance, affects the behavior of the steel beams and may reduce their ultimate capacity. To obtain this effect, finite element modeling (FEM) was used to model these beams with and without an out-of-plane distance at the mid-span beam length with several different variables. These variables were the out-of-plane distance, cross-section dimensions, beam length, and steel yield stress. The reliability of using FEM simulation was confirmed by comparing the experimental test results of 25 available steel beams in previous studies. The results indicate the high accuracy of the simulation of this beam in terms of ultimate capacity, structural behavior, and deformation patterns. After verifying the results, 116 broad-flange I-beam (BFIB) steel beams with different out-of-plane distances were modeled. The results showed that using an out-of-plane distance equal to the flange width of the BFIB-300 cross-section caused a 60% decrease in the ultimate capacity. The reduction ratios in the ultimate moment capacity in out-of-plane steel beams were directly proportional to the out-of-plane distance, cross-sectional dimensions, and steel yield stress, while the beam length had no effect. Failure in beams containing an out-of-plane distance occurs as a result of a global buckling in the upper flange, which contains tensile stresses at the outer edge and compressive stresses at the inner edge, with stress concentration occurring at the point of contact of the out-of-plane part with the main beam. The prediction results of the design codes were compared with the results of experimental tests and the FEM analysis of the beams with and without out-of-plane distances. For all the beams with out-of-plane distances, all the design codes were unable to predict this ultimate capacity. [ABSTRACT FROM AUTHOR]

Featured Application: Patient-specific finite element models of degenerative cervical myelopathy (DCM) patients correlate with neurological function, assess disease severity, and can potentially guide personalized surgical planning. Degenerative cervical myelopathy (DCM) is characterized by progressive neurological dysfunction, yet the contribution of intramedullary stress and strain during neck motion remains unclear. This study used patient-specific finite element models (FEMs) of the cervical spine and spinal cord to examine the relationship between spinal cord biomechanics and neurological dysfunction. Twenty DCM patients (mean age 62.7 ± 11.6 years; thirteen females) underwent pre-surgical MRI-based modeling to quantify von Mises stress and maximum principal strains at the level of maximum spinal cord compression during simulated neck flexion and extension. Pre-surgical functional assessments included hand sensation, dexterity, and balance. During flexion, the mean intramedullary stress and strain at the level of maximum compression were 7.6 ± 3.7 kPa and 4.3 ± 2.0%, respectively. Increased intramedullary strain during flexion correlated with decreased right-hand sensation (r = −0.58, p = 0.014), impaired right-hand dexterity (r = −0.50, p = 0.048), and prolonged dexterity time (r = 0.52, p = 0.039). Similar correlations were observed with intramedullary stress. Patients with severe DCM exhibited significantly greater stress during flexion than those with mild/moderate disease (p = 0.03). These findings underscore the impact of dynamic spinal cord biomechanics on neurological dysfunction and support their potential utility in improving DCM diagnosis and management. [ABSTRACT FROM AUTHOR]

Ultra-precision lapping is widely used in the mass production of various types of high-precision bearing rollers. The lapping quality of the bearing rollers is greatly influenced by the wear behavior of the lapping tool. In this context, this study presents a computational analysis utilizing the Archard wear law and finite element modeling (FEM) to examine the wear behavior of the lapping tool. A wear simulation approach based on the Archard wear law is implemented in the ABAQUS software that works in association with the Arbitrary Lagrange Eulerian adaptive mesh technique and the Umeshmotion subroutine. Initially, the parameters of the Archard wear model are investigated experimentally using the free abrasive lapping device. A numerical 3D finite element model is established in order to obtain the contact pressure distribution, wear volume, wear depth, and wear profile of the lapping tool. The mesh within the wear region of the finite element model is allowed to move independently from the material to maintain the high-quality mesh for simulating material removal. The simulation efficiency is improved by the incorporation of an acceleration factor. Ultimately, the lapping tool is subjected to an examination regarding the contact pressure distribution, wear depth, and alterations in the wear profile. The wear simulation results of the lapping tool can provide significant insights for future run-in and machining processes. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer (FRP) composites are increasingly used in civil engineering for strengthening and repairing existing reinforced concrete (RC) members using externally bonded reinforcement (EBR) and near-surface mounted (NSM) methods. However, the fire performance of FRP-strengthened RC members has been an important issue that should be properly considered in the fire safety design process since FRP composites exhibit significant performance degradation at elevated temperatures. This paper aims to review studies on the fire performance of FRP-strengthened RC members based on the existing research results presented in the literature to provide a comprehensive understanding of key factors influencing the structural behavior of FRP-strengthened RC members under fire conditions. It provides an overview of FRP composite material properties, such as their mechanical and thermal behavior and bond characteristics between FRP-to-concrete interfaces at elevated temperatures. Additionally, this paper reviews experimental and numerical research conducted on FRP-strengthened RC members, examining load-carrying capacities and fire endurance ratings. Finally, this review will provide existing fire resistance design methods as well as simple design methods for temperature prediction. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of a nonlinear static deformation on the dynamic aeroelastic behavior of very flexible wings. The objects of study are the Pre-Pazy and Pazy wings, which are highly flexible wings presented by the Large Deflections Working Group of the Third Aeroelastic Prediction Workshop. A nonlinear static aeroelastic coupling analysis is performed, coupling a nonlinear beam formulation with the Vortex Lattice Method. The natural frequencies and mode shapes of the wing are obtained considering the predeformed structure, and these results serve as input data for the dynamic aeroelastic model, which considers the Unsteady Vortex Lattice Method as the aerodynamic model and serves to yield the aeroelastic responses in modal coordinates. The frequency spectrum of each time response serves as input for a system identification method, which considers the Least Squares Complex Frequency-domain estimator. The velocity-damping-frequency diagrams are obtained from the identified frequencies and damping ratios, and the critical flutter condition is determined. The flutter speeds obtained agree with the references, and the differences are up to 77% for the Pre-Pazy wing and 4% for the Pazy wing. A significant reduction in those speeds is observed with an increase in the angle of attack. [ABSTRACT FROM AUTHOR]

This paper deals with the analysis of wave propagation characteristics in various prestressed structures with geometric nonlinearities using the Carrera Unified Formulation (CUF). CUF provides a versatile platform to model a wide range of structures and nonlinearities that can take care of all wave propagation aspects. In this work, different geometric nonlinearities for which representative governing equations have been derived and numerical solutions have been obtained through a unified approach are considered. The study investigates in detail the effect of prestress and geometric nonlinearity on wave propagation behavior. The results indicate that prestress has a very influential effect on modal frequency and dispersion characteristics for wave propagation. Specifically, three CUF-modeled beams are considered herein, having a sandwich, metallic portal, and metallic box cross section, respectively. Initially, the principal cross-sectional modal shapes of the unstressed, linear, and full nonlinear (i.e., full three-dimensional Green-Lagrange strain matrix) beam with a prestress are investigated, among which torsional and flexural modes can be recognized. Afterward, the equilibrium curves of such structures for various geometrical nonlinear approximations are traced, highlighting that most types of nonlinearity induce a hardening behavior in the system, which increases with the preload, directly leading to a variation in modal frequencies. The dispersion relations of the full nonlinear structure examined as a function of the applied preload are further compared, enriching the investigation by exploiting wave finite element method capabilities. This knowledge paves the way toward the design and optimization of prestressed systems with enhanced acoustic performance, and that fosters the development of sound absorption, noise insulation, and structural isolation. [ABSTRACT FROM AUTHOR]

Temperature-induced cracks during the construction of large concrete structures, such as water gates and bridges, caused by hydration heat, pose a serious threat to structural safety and reliability. To address this, various countries have developed temperature control standards and guidelines for mass concrete structures, providing design direction and evaluation criteria. China and the United States (U.S.) are leaders in the field of temperature control for mass concrete structures, with significant influence in international projects. The study of the differences in temperature control results between the two countries' standards not only helps to understand the impact of different regulations on temperature control design but also provides more design options for multinational projects. This study uses ABAQUS software (version 2023)to establish a finite element model of a water gate and employs secondary development of ABAQUS to simulate the temperature and stress fields under both Chinese and U.S. standards. The results indicate that the overall temperature and stress distributions of the structure are similar under both standards. The calculation results for internal and surface characteristic points show that the maximum temperature predicted by the Chinese standard is slightly higher than that of the U.S. standard, with a difference of no more than 1.7 °C. However, the maximum tensile stress calculated under the Chinese standard is lower than that of the U.S. standard, with internal stress differences not exceeding 0.23 MPa and surface stress differences not exceeding 0.56 MPa. This study provides a direct comparison of the temperature control results between the two standards, offering valuable insights for international projects to balance cost and safety, while also providing empirical evidence for optimizing national standards. [ABSTRACT FROM AUTHOR]

This research investigates the seismic behavior of rigid and flexible cylindrical steel tanks, focusing on tanks with an open top and fully anchored at the base. The primary objective is to evaluate the hydrodynamic pressures exerted by the fluid on the tank walls during seismic excitation. Three widely recognized design approaches—New Zealand NZSEE recommendations, European code UNI EN 1998-4:2006 (CEN, 2006), and American Water Works Association AWWA D100-05 standard (ANSI/AWWA, 2005)—were implemented and compared with high-definition finite element models and then validated against the experimental results. Nonlinear fluid–structure interaction (FSI) was modeled using an Arbitrary Lagrangian–Eulerian (ALE) formulation with the Navier–Stokes equations governing the fluid motion and material and geometric nonlinearities considered in the tank walls. Parametric analyses were conducted to investigate the impact of tank geometry, specifically height-to-radius and radius-to-thickness ratios, on seismic response, identifying a transition between rigid and flexible behavior. The study also examined the influence of seismic input using a set of ten displacement spectrum-compatible ground motions. The findings contribute to a better understanding of the seismic resilience of cylindrical steel tanks, offering valuable insights for improving design standards and safety in earthquake-prone regions where these systems may abound. [ABSTRACT FROM AUTHOR]